Fixed facilitated transport of CO2 through integrally-skinned asymmetric polyethersulfone membrane using a novel synthesized Poly (acrylonitrile-co-N, N-Dimethylaminopropyl acrylamide)

• A novel water insoluble PAN-PDMAPAM copolymer was synthesized.
• The synthesized copolymer was used as a carrier for CO2 in asymmetric PES membrane.
• Morphology and plasticization pressure of membranes were affected by the carrier.
• CO2 sorption, CO2 permeance and CO2/CH4 selectivity were increased by the PAN.
• A CO2/CH4 separation factor of up to 39 was documented.

In the current study, a novel water insoluble Poly (acrylonitrile-co-N, N-Dimethylaminopropyl acrylamide) [PAN-PDMAPAM] copolymer was synthesized and employed as a CO2 carrier in an integrally-skinned asymmetric polyethersulfone (PES) membrane. The membranes provided the facilitated transport in addition to the solution–diffusion mechanism in PES membranes for the separation of CO2 from CH4. Differential Scanning Calorimetry was used for investigating the change in the glass transition temperature of the PES and miscibility of the PES and synthesized PAN-PDMAPAM. Scanning Electron Microscopy (SEM) and porosity measurement were used to study the effect of PAN-PDMAPAM on the membrane morphology. The effects of the synthesized PAN-PDMAPAM on the gas sorption capacity and the dual-mode parameter of the PES membranes were studied using sorption isotherms. The addition of PAN-PDMAPAM changes the morphology, increases the CO2 sorption capacity and decreases the glass transition temperature (Tg) as well as Langmuir sorption sites of the prepared PES membranes. An improvement can be seen in the plasticization when the PAN-PDMAPAM concentration was 0.5 and 1 wt.%. Introducing the PAN-PDMAPAM in PES membranes significantly improves the membrane performance including CO2 permeance and CO2/CH4 selectivity because of the incorporation of the facilitated transport of CO2. The addition of PAN-PDMAPAM in the PES membranes changes the behavior of the PES membrane against the feed temperature and the feed pressure. It was shown that the application of PES/PAN-PDMAPAM membranes is limited to ambient temperature because at the elevated temperatures, the equilibrium constant of the facilitated transport reaction is small, and hence the permeation of CO2 decreases.